Fabrication of a bi-metallic component for an aerospace mechanism by laser cladding

Designers wanted a particular component to be made of two materials (a) aluminium bronze and (b) nitriding steel. The former provides the necessary tribological properties (low coefficient of friction) and the latter the required mechanical strength. It has been decided to attempt it through laser cladding. Prior to the fabrication, a detailed parametric study for optimising laser cladding of aluminium bronze on nitriding steel has been carried out. A processing window has been established. Within the parametric range of the processing window, by appropriate control of process variables, it is possible to control clad overlay thickness between 0.27 mm to 1.13 mm. Effect of processing variables on other clad parameters like depth of fusion zone, width, aspect ratio, dilution and heat affected zone have been studied. Lower power densities (0.1 to 1kW.mm(-2)) and higher interaction time (0.19s to 0.87s) lead to good clads. Certain peculiar observations such as formation of iron rich globules have been investigated and explained.